Title: Neutron-Capture Element Abundances of Open Clusters at Rgc 9-12 kpc in the Milky Way Disk

Abstract: We have undertaken a study of Ba, La and Eu abundances of a large sample of open clusters spanning the full radial extent of the Galactic disk. To our knowledge, only barium abundances have been determined for a large sample of clusters in a self-consistent fashion, and an unexpected trend of increasing [Ba/Fe] with decreasing cluster age was found (D'Orazi et al. 2009). This trend should be looked for in other large cluster samples and in other neutron-capture elements. More generally, the relative abundances of r- and s-process elements determined in an homogeneous fashion for many open clusters will provide more information regarding the chemical enrichment history of the Milky Way disk. We request KPNO 4m time to obtain high resolution echelle spectroscopy of stars in four key clusters in our sample that lie in the transition region, R_gc$~9-12 kpc, in order to determine their neutron-capture abundances.